Wet chemical etching methods of structuring wafers are already known. A photoresist method is generally used to define a structure. Increasing quality demands in production of integrated circuits and micromechanical sensor arrangements require removal of the photoresist from the wafers used, because otherwise residues of resist will be entrained throughout the various process steps in conveyance of the wafers. However, after the resist has been removed from the edge of the wafer, it is unprotected when exposed to etchant media.
The method according to the present invention has the advantage that passivation of the wafer edge is guaranteed despite removal of the resist there without having to use etching boxes, for example, to protect the wafer edge from the aggressive etchant medium. By combining wafer edge passivation as a negative process with the positive process of determining the areas to be etched subsequently, a method is provided which is inexpensive and nevertheless meets high quality demands. The wafer edge remains protected from etchant media without photoresist at the edge and without the use of etching boxes.
By removing a nitride layer only in subareas and then applying a thin passivation layer in the subareas, two or more step etching processes can also be carried out while preserving the wafer edge passivation.
It is especially advantageous to use an oxide layer as a passivation layer, which is applied in a LOCOS process (LOCOS=xe2x80x9clocal oxidation of siliconxe2x80x9d).